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Hui W, Pu S, Gao X, Wang Y, Zha X, Ding K, Zhang X, Cheng D, Shi H, Luo Z. Evaluation of a Positron Emission Tomography Tracer Targeting Colony-Stimulating Factor 1 Receptor for Detecting Pulmonary Inflammation. Mol Pharm 2024; 21:3979-3991. [PMID: 38935927 DOI: 10.1021/acs.molpharmaceut.4c00337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/29/2024]
Abstract
Colony-stimulating factor 1 receptor (CSF1R) is a type III receptor tyrosine kinase that is crucial for immune cell activation, survival, proliferation, and differentiation. Its expression significantly increases in macrophages during inflammation, playing a crucial role in regulating inflammation resolution and termination. Consequently, CSF1R has emerged as a critical target for both therapeutic intervention and imaging of inflammatory diseases. Herein, we have developed a radiotracer, 1-[4-((7-(dimethylamino)quinazolin-4-yl)oxy)phenyl]-3-(4-[18F]fluorophenyl)urea ([18F]17), for in vivo positron emission tomography (PET) imaging of CSF1R. Compound 17 exhibits a comparable inhibitory potency against CSF1R as the well-known CSF1R inhibitor PLX647. The radiosynthesis of [18F]17 was successfully performed by radiofluorination of aryltrimethyltin precursor with a yield of approximately 12% at the end of synthesis, maintaining a purity exceeding 98%. In vivo stability and biodistribution studies demonstrate that [18F]17 remains >90% intact at 30 min postinjection, with no defluorination observed even at 60 min postinjection. The PET/CT imaging study in lipopolysaccharide-induced pulmonary inflammation mice indicates that [18F]17 offers a more sensitive characterization of pulmonary inflammation compared to traditional [18F]FDG. Notably, [18F]17 shows a higher discrepancy in uptake ratio between mice with pulmonary inflammation and the sham group. Furthermore, the variations in [18F]17 uptake ratio observed on day 7 and day 14 correspond to lung density changes observed in CT imaging. Moreover, the expression levels of CSF1R on day 7 and day 14 follow a trend similar to the uptake pattern of [18F]17, indicating its potential for accurately characterizing CSF1R expression levels and effectively monitoring the pulmonary inflammation progression. These results strongly suggest that [18F]17 has promising prospects as a CSF1R PET tracer, providing diagnostic opportunities for pulmonary inflammatory diseases.
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Affiliation(s)
- Wenxue Hui
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Suyun Pu
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xinyan Gao
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yunze Wang
- Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Xiaochuan Zha
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Kezhi Ding
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaoyu Zhang
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
| | - Dengfeng Cheng
- Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Hongcheng Shi
- Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Zonghua Luo
- School of Biomedical Engineering & State Key Laboratory of Advanced Medical Materials and Devices, ShanghaiTech University, Shanghai 201210, China
- Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, China
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Chauveau F, Winkeler A, Chalon S, Boutin H, Becker G. PET imaging of neuroinflammation: any credible alternatives to TSPO yet? Mol Psychiatry 2024:10.1038/s41380-024-02656-9. [PMID: 38997465 DOI: 10.1038/s41380-024-02656-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/26/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.
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Affiliation(s)
- Fabien Chauveau
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
| | - Alexandra Winkeler
- Université Paris-Saclay, Inserm, CNRS, CEA, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401, Orsay, France
| | - Sylvie Chalon
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France
| | - Hervé Boutin
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France.
| | - Guillaume Becker
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
- Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail, 14 rue Pierre et Marie Curie, 94701, Maisons-Alfort, Cedex, France
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3
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Lee N, Choi JY, Ryu YH. The development status of PET radiotracers for evaluating neuroinflammation. Nucl Med Mol Imaging 2024; 58:160-176. [PMID: 38932754 PMCID: PMC11196502 DOI: 10.1007/s13139-023-00831-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/16/2023] [Accepted: 12/05/2023] [Indexed: 06/28/2024] Open
Abstract
Neuroinflammation is associated with the pathophysiologies of neurodegenerative and psychiatric disorders. Evaluating neuroinflammation using positron emission tomography (PET) plays an important role in the early diagnosis and determination of proper treatment of brain diseases. To quantify neuroinflammatory responses in vivo, many PET tracers have been developed using translocator proteins, imidazole-2 binding site, cyclooxygenase, monoamine oxidase-B, adenosine, cannabinoid, purinergic P2X7, and CSF-1 receptors as biomarkers. In this review, we introduce the latest developments in PET tracers that can image neuroinflammation, focusing on clinical trials, and further consider their current implications.
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Affiliation(s)
- Namhun Lee
- Division of Applied RI, Korea Institute of Radiological & Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 01812 Korea
| | - Jae Yong Choi
- Division of Applied RI, Korea Institute of Radiological & Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 01812 Korea
- Radiological and Medico-Oncological Sciences, University of Science and Technology (UST), Seoul, Korea
| | - Young Hoon Ryu
- Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Jiang H, Roy P, Guo Y, Muzik O, Woodcock EA. Automated radiosynthesis of [ 11C]CPPC for in-human PET imaging applications. AMERICAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING 2024; 14:144-148. [PMID: 38737641 PMCID: PMC11087290 DOI: 10.62347/mxkz6739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 04/08/2024] [Indexed: 05/14/2024]
Abstract
The macrophage colony-stimulating factor 1 receptor (CSF1R) is almost exclusively expressed in microglia, representing a biomarker target for imaging of microglia availability. [11C]CPPC has specific binding affinity to CSF1R and suitable kinetic properties for in vivo PET imaging of microglia. However, previous studies reported a low radiochemical yield, motivating additional research to optimize [11C]CPPC radiochemistry. In this work, we report an automated radiosynthesis of [11C]CPPC on a Synthra MeIPlus module with improved radiochemical yield. The final [11C]CPPC product was obtained with excellent chemical/radiochemical purities and molecular activity, facilitating high-quality in-human PET imaging applications.
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Affiliation(s)
- Huailei Jiang
- Cyclotron and Radiochemistry Core, Karmanos Cancer InstituteDetroit, MI, USA
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Oncology, Wayne State UniversityDetroit, MI, USA
| | - Pritam Roy
- Cyclotron and Radiochemistry Core, Karmanos Cancer InstituteDetroit, MI, USA
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Oncology, Wayne State UniversityDetroit, MI, USA
| | - Yan Guo
- Cyclotron and Radiochemistry Core, Karmanos Cancer InstituteDetroit, MI, USA
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Oncology, Wayne State UniversityDetroit, MI, USA
| | - Otto Muzik
- PET Center, Karmanos Cancer InstituteDetroit, MI, USA
- Department of Pediatrics and Neurology, Wayne State UniversityDetroit, MI, USA
| | - Eric A Woodcock
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of MedicineDetroit, MI, USA
- Department of Pharmacology, Wayne State University School of MedicineDetroit, MI, USA
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5
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Bobotis BC, Halvorson T, Carrier M, Tremblay MÈ. Established and emerging techniques for the study of microglia: visualization, depletion, and fate mapping. Front Cell Neurosci 2024; 18:1317125. [PMID: 38425429 PMCID: PMC10902073 DOI: 10.3389/fncel.2024.1317125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/15/2024] [Indexed: 03/02/2024] Open
Abstract
The central nervous system (CNS) is an essential hub for neuronal communication. As a major component of the CNS, glial cells are vital in the maintenance and regulation of neuronal network dynamics. Research on microglia, the resident innate immune cells of the CNS, has advanced considerably in recent years, and our understanding of their diverse functions continues to grow. Microglia play critical roles in the formation and regulation of neuronal synapses, myelination, responses to injury, neurogenesis, inflammation, and many other physiological processes. In parallel with advances in microglial biology, cutting-edge techniques for the characterization of microglial properties have emerged with increasing depth and precision. Labeling tools and reporter models are important for the study of microglial morphology, ultrastructure, and dynamics, but also for microglial isolation, which is required to glean key phenotypic information through single-cell transcriptomics and other emerging approaches. Strategies for selective microglial depletion and modulation can provide novel insights into microglia-targeted treatment strategies in models of neuropsychiatric and neurodegenerative conditions, cancer, and autoimmunity. Finally, fate mapping has emerged as an important tool to answer fundamental questions about microglial biology, including their origin, migration, and proliferation throughout the lifetime of an organism. This review aims to provide a comprehensive discussion of these established and emerging techniques, with applications to the study of microglia in development, homeostasis, and CNS pathologies.
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Affiliation(s)
- Bianca Caroline Bobotis
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Centre for Advanced Materials and Related Technology, Victoria, BC, Canada
| | - Torin Halvorson
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada
- Department of Surgery, University of British Columbia, Vancouver, BC, Canada
- British Columbia Children’s Hospital Research Institute, Vancouver, BC, Canada
| | - Micaël Carrier
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Département de Psychiatrie et de Neurosciences, Faculté de Médecine, Université Laval, Québec City, QC, Canada
- Axe neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
| | - Marie-Ève Tremblay
- Division of Medical Sciences, University of Victoria, Victoria, BC, Canada
- Centre for Advanced Materials and Related Technology, Victoria, BC, Canada
- Axe neurosciences, Centre de Recherche du CHU de Québec, Université Laval, Québec City, QC, Canada
- Department of Molecular Medicine, Université Laval, Québec City, QC, Canada
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6
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Mills KA, Du Y, Coughlin JM, Foss CA, Horti AG, Jenkins K, Skorobogatova Y, Spiro E, Motley CS, Dannals RF, Song JJ, Choi YR, Redding-Ochoa J, Troncoso J, Dawson VL, Kam TI, Pomper MG, Dawson TM. Exploring [ 11C]CPPC as a CSF1R-targeted PET Imaging Marker for Early Parkinson's Disease Severity. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2023.05.28.23290647. [PMID: 37398476 PMCID: PMC10312881 DOI: 10.1101/2023.05.28.23290647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Neuroinflammation through enhanced innate immunity is thought play a role in the pathogenesis of Parkinson's disease (PD). Methods for monitoring neuroinflammation in living patients with PD are currently limited to positron emission tomography (PET) ligands that lack specificity in labeling immune cells in the nervous system. The colony stimulating factor 1 receptor (CSF1R) plays a crucial role in microglial function, an important cellular contributor to the nervous system's innate immune response. Using immunologic methods, we show that CSF1R in human brain is colocalized with the microglial marker, ionized calcium binding adaptor molecule 1 (Iba1). In PD, CSF1R immunoreactivity is significantly increased in PD across multiple brain regions, with the largest differences in the midbrain versus controls. Autoradiography revealed significantly increased [3H]JHU11761 binding in the inferior parietal cortex of PD patients. PET imaging demonstrated that higher [11C]CPPC binding in the striatum was associated with greater motor disability in PD. Furthermore, increased [11C]CPPC binding in various regions correlated with more severe motor disability and poorer verbal fluency. This study finds that CSF1R expression is elevated in PD and that [11C]CPPC-PET imaging of CSF1R is indicative of motor and cognitive impairments in the early stages of the disease. Moreover, the study underscores the significance of CSF1R as a promising biomarker for neuroinflammation in Parkinson's disease, suggesting its potential use for non-invasive assessment of disease progression and severity, leading to earlier diagnosis and targeted interventions.
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Affiliation(s)
- Kelly A Mills
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Yong Du
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
| | - Jennifer M Coughlin
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Catherine A Foss
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
| | - Andrew G Horti
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
| | - Katelyn Jenkins
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Yana Skorobogatova
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
| | - Ergi Spiro
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
| | - Chelsie S Motley
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Robert F Dannals
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
| | - Jae-Jin Song
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yu Ree Choi
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Javier Redding-Ochoa
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Juan Troncoso
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Valina L Dawson
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Tae-In Kam
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Martin G Pomper
- Johns Hopkins University School of Medicine, Russell H. Morgan Dept. of Radiology and Radiologic Science, Baltimore, MD, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, US
- Department of Radiology, University of Texas Southwestern School of Medicine, Dallas, TX, USA (current)
| | - Ted M Dawson
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
- Neuroregeneration and Stem Cell Programs, Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, US
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Etebar F, Harkin DG, White AR, Dando SJ. Non-invasive in vivo imaging of brain and retinal microglia in neurodegenerative diseases. Front Cell Neurosci 2024; 18:1355557. [PMID: 38348116 PMCID: PMC10859418 DOI: 10.3389/fncel.2024.1355557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/10/2024] [Indexed: 02/15/2024] Open
Abstract
Microglia play crucial roles in immune responses and contribute to fundamental biological processes within the central nervous system (CNS). In neurodegenerative diseases, microglia undergo functional changes and can have both protective and pathogenic roles. Microglia in the retina, as an extension of the CNS, have also been shown to be affected in many neurological diseases. While our understanding of how microglia contribute to pathological conditions is incomplete, non-invasive in vivo imaging of brain and retinal microglia in living subjects could provide valuable insights into their role in the neurodegenerative diseases and open new avenues for diagnostic biomarkers. This mini-review provides an overview of the current brain and retinal imaging tools for studying microglia in vivo. We focus on microglia targets, the advantages and limitations of in vivo microglia imaging approaches, and applications for evaluating the pathogenesis of neurological conditions, such as Alzheimer's disease and multiple sclerosis.
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Affiliation(s)
- Fazeleh Etebar
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Damien G. Harkin
- Centre for Vision and Eye Research, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - Anthony R. White
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Samantha J. Dando
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
- Centre for Vision and Eye Research, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
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Altomonte S, Pike VW. Candidate Tracers for Imaging Colony-Stimulating Factor 1 Receptor in Neuroinflammation with Positron Emission Tomography: Issues and Progress. ACS Pharmacol Transl Sci 2023; 6:1632-1650. [PMID: 37974622 PMCID: PMC10644394 DOI: 10.1021/acsptsci.3c00213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Indexed: 11/19/2023]
Abstract
The tyrosine kinase, colony-stimulating factor 1 receptor (CSF1R), has attracted attention as a potential biomarker of neuroinflammation for imaging studies with positron emission tomography (PET), especially because of its location on microglia and its role in microglia proliferation. The development of an effective radiotracer for specifically imaging and quantifying brain CSF1R is highly challenging. Here we review the progress that has been made on PET tracer development and discuss issues that have arisen and which remain to be addressed and resolved.
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Affiliation(s)
- Stefano Altomonte
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes
of Health, Building 10,
B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes
of Health, Building 10,
B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
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Myburgh PJ, Sai KKS. Development and Optimization of 11C-Labeled Radiotracers: A Review of the Modern Quality Control Design Process. ACS Pharmacol Transl Sci 2023; 6:1616-1631. [PMID: 37974626 PMCID: PMC10644505 DOI: 10.1021/acsptsci.3c00200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Indexed: 11/19/2023]
Abstract
Introduction - Several 11C-tracers have demonstrated high potential in early diagnostic PET imaging applications of neurodegenerative diseases including Alzheimer's and Parkinson's disease. These radiotracers often track critical biomarkers in disease pathogenesis such as tau fibrils ([11C]PBB3) or β-amyloid plaques ([11C]PiB) associated with such diseases. Purpose - The short review aims to serve as a guideline in the future development of radiotracers for students, postdocs and/or new radiochemists who will be synthesizing clinical grade or novel research 11C-tracers, including knowledge of regulatory requirements. We aim to bridge the gap between novel and established 11C-tracer quality control (QC) processes through exploring the design process and regulatory requirements for 11C-pharmaceuticals. Methods - A literature survey was undertaken to identify articles with a detailed description of the QC methodology and characterization for each of the sections of the review. Overview - First a general summary of 11C-tracer production was presented; this was used to establish possible places for contamination or assurances for a sterile final product. The key mandated QC analyses for clinical use were then discussed. Further, we assessed the QC methods used for established 11C-tracers and then reviewed the routine QC tests for preclinical translational and validation studies. Therefore, both mandated QC methods for clinical and preclinical animal studies were reviewed. Last, some examples of optimization and automation were reviewed, and implications of the QC practices associated with such procedures were considered. Conclusion - All of the common QC parameters associated with 11C-tracers under clinical and preclinical settings (along with a few exceptions) were discussed in detail. While it is important to establish standard, peer-reviewed QC testing protocols for a novel 11C-tracer entering the clinical umbrella, equal importance is needed on preclinical applications to address credibility and repeatability for the study.
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Affiliation(s)
- Paul Josef Myburgh
- Translational
Imaging Program, Atrium Health Wake Forest
Baptist Medical Center, Winston-Salem, North Carolina 27157, United States
| | - Kiran Kumar Solingapuram Sai
- Translational
Imaging Program, Atrium Health Wake Forest
Baptist Medical Center, Winston-Salem, North Carolina 27157, United States
- Department
of Radiology, Atrium Health Wake Forest
Baptist Medical Center, Winston-Salem, North Carolina 27157, United States
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Rubin LH, Du Y, Sweeney SE, O’Toole R, Harrington CK, Jenkins K, Lesniak WG, Veenhuis RT, Dastgheyb R, Severson J, Fan H, Holt DP, Hall AW, Dannals RF, Horti AG, Pomper MG, Coughlin JM. Pilot imaging of the colony stimulating factor 1 receptor in the brains of virally-suppressed individuals with HIV. AIDS 2023; 37:1419-1424. [PMID: 37070549 PMCID: PMC10330113 DOI: 10.1097/qad.0000000000003572] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/19/2023]
Abstract
OBJECTIVE Neuroimmune activation is a putative driver of cognitive impairment in people with HIV (PWH), even in the age of modern antiretroviral therapy. Nevertheless, imaging of the microglial marker, the 18 kDa translocator protein (TSPO), with positron emission tomography (PET) in treated PWH has yielded inconclusive findings. One potential reason for the varied TSPO results is a lack of cell-type specificity of the TSPO target. DESIGN [ 11 C]CPPC, 5-cyano- N -(4-(4-[ 11 C]methylpiperazin-1-yl)-2-(piperidin-1-yl)phenyl) furan-2-carboxaminde, is a radiotracer for use with PET to image the colony stimulating factor 1 receptor (CSF1R). The CSF1R is expressed on microglia and central nervous system macrophages, with little expression on other cell types. We used [ 11 C]CPPC PET in virally-suppressed- (VS)-PWH and HIV-uninfected individuals to estimate the effect sizes of higher CSF1R in the brains of VS-PWH. METHODS Sixteen VS-PWH and 15 HIV-uninfected individuals completed [ 11 C]CPPC PET. [ 11 C]CPPC binding (V T ) in nine regions was estimated using a one-tissue compartmental model with a metabolite-corrected arterial input function, and compared between groups. RESULTS Regional [ 11 C]CPPC V T did not significantly differ between groups after age- and sex- adjustment [unstandardized beta coefficient ( B ) = 1.84, standard error (SE) = 1.18, P = 0.13]. The effect size was moderate [Cohen's d = 0.56, 95% confidence interval (CI) -0.16, 1.28), with strongest trend of higher V T in VS-PWH in striatum and parietal cortex (each P = 0.04; Cohen's d = 0.71 and 0.72, respectively). CONCLUSIONS A group difference in [ 11 C]CPPC V T was not observed between VS-PWH and HIV-uninfected individuals in this pilot, although the observed effect sizes suggest the study was underpowered to detect regional group differences in binding.
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Affiliation(s)
- Leah H. Rubin
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Department of Epidemiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Molecular and Comparative Pathobiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Yong Du
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Shannon Eileen Sweeney
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Riley O’Toole
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Courtney K. Harrington
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Katelyn Jenkins
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Wojciech G. Lesniak
- Department of Epidemiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Rebecca T. Veenhuis
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Molecular and Comparative Pathobiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Raha Dastgheyb
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | | | - Hong Fan
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Daniel P. Holt
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Andrew W. Hall
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Robert F. Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Andrew G. Horti
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Martin G. Pomper
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Molecular and Comparative Pathobiology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins Medical Institutions, Baltimore, MD, USA
| | - Jennifer M. Coughlin
- Department of Neurology, Johns Hopkins Medical Institutions, Baltimore, MD, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins Medical Institutions, Baltimore, MD, USA
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11
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Parker CA, Nutt DJ, Tyacke RJ. Imidazoline-I2 PET Tracers in Neuroimaging. Int J Mol Sci 2023; 24:9787. [PMID: 37372936 DOI: 10.3390/ijms24129787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/24/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023] Open
Abstract
Targeting neuroinflammation, and in particular, microglial activation and astrocytosis, is a current area of the focus of new treatment interventions for a number of neurodegenerative disorders. Probing the roles of microglia and astrocytes in human disease requires the development of useful tools, such as PET imaging tools that are specific for the cell type(s) of interest. This review concentrates on the recent advances in the development of Imidazoline2 binding site (I2BS) PET tracers, which are purported to target astrocytes, and hence could represent key clinical imaging tools for targeting astrocytes in neurodegenerative disease. Five PET tracers for the I2BS are described in this review, with only one (11C-BU99008) being currently validated to GMP for clinical use, and data reported from healthy volunteers, Alzheimer's disease patients, and Parkinson's disease patients. The clinical data utilising 11C-BU99008 have revealed the potential early involvement of astrogliosis in neurodegeneration that might precede the activation of microglia, which, if confirmed, could provide a vital new means for potentially targeting neurodegeneration earlier in the disease course.
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Affiliation(s)
- Christine A Parker
- Neuropsychopharmacology Unit, Division of Psychiatry, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
- GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, UK
| | - David J Nutt
- Neuropsychopharmacology Unit, Division of Psychiatry, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
| | - Robin J Tyacke
- Neuropsychopharmacology Unit, Division of Psychiatry, Imperial College London, Hammersmith Hospital Campus, Du Cane Road, London W12 0NN, UK
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12
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Altomonte S, Yan X, Morse CL, Liow JS, Jenkins MD, Montero Santamaria JA, Zoghbi SS, Innis RB, Pike VW. Discovery of a High-Affinity Fluoromethyl Analog of [ 11C]5-Cyano- N-(4-(4-methylpiperazin-1-yl)-2-(piperidin-1-yl)phenyl)furan-2-carboxamide ([ 11C]CPPC) and Their Comparison in Mouse and Monkey as Colony-Stimulating Factor 1 Receptor Positron Emission Tomography Radioligands. ACS Pharmacol Transl Sci 2023; 6:614-632. [PMID: 37082755 PMCID: PMC10111626 DOI: 10.1021/acsptsci.3c00003] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Indexed: 03/12/2023]
Abstract
[11C]CPPC has been advocated as a radioligand for colony-stimulating factor 1 receptor (CSF1R) with the potential for imaging neuroinflammation in human subjects with positron emission tomography (PET). This study sought to prepare fluoro analogs of CPPC with higher affinity to provide the potential for labeling with longer-lived fluorine-18 (t 1/2 = 109.8 min) and for delivery of higher CSF1R-specific PET signal in vivo. Seven fluorine-containing analogs of CPPC were prepared and four were found to have high inhibitory potency (IC50 in low to sub-nM range) and selectivity at CSF1R comparable with CPPC itself. One of these, a 4-fluoromethyl analog (Psa374), was investigated more deeply by labeling with carbon-11 (t 1/2 = 20.4 min) for PET studies in mouse and monkey. [11C]Psa374 showed high peak uptake in monkey brain but not in mouse brain. Pharmacological challenges revealed no CSF1R-specific binding in either species at baseline. [11C]CPPC also failed to show specific binding at baseline. Moreover, both [11C]Psa374 and [11C]CPPC showed brain efflux transporter substrate behavior in both species in vivo, although Psa374 did not show liability toward human efflux transporters in vitro. Further development of [11C]Psa374 in non-human primate models of neuroinflammation with demonstration of CSF1R-specific binding would be required to warrant the fluorine-18 labeling of Psa374 with a view to possible application in human subjects.
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Affiliation(s)
- Stefano Altomonte
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Xuefeng Yan
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Cheryl L. Morse
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Jeih-San Liow
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Madeline D. Jenkins
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Jose A. Montero Santamaria
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Sami S. Zoghbi
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Robert B. Innis
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Victor W. Pike
- Molecular Imaging Branch,
National Institute of Mental Health, National
Institutes of Health Building 10, B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
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13
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An X, Wang J, Tong L, Zhang X, Fu H, Zhang J, Xie H, Huang Y, Jia H. 18F-Labeled o‑aminopyridyl alkynyl radioligands targeting colony-stimulating factor 1 receptor for neuroinflammation imaging. Bioorg Med Chem 2023; 83:117233. [PMID: 36933438 DOI: 10.1016/j.bmc.2023.117233] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/24/2023] [Accepted: 03/02/2023] [Indexed: 03/09/2023]
Abstract
We report the design, synthesis and evaluation of five o‑aminopyridyl alkynyl derivatives as colony-stimulating factor 1 receptor (CSF-1R) ligands. Compounds 4 and 5 with the fluoroethoxy group at the meta- or para-position of the phenyl ring possessed nanomolar inhibitory potency against CSF-1R with IC50 values of 7.6 nM and 2.3 nM, respectively. Radioligands [18F]4 and [18F]5 were obtained in radiochemical yields of 17.2 ± 5.3% (n = 5, decay-corrected) and 14.0 ± 4.3% (n = 4, decay-corrected), with radiochemical purity of > 99% and molar activity of 9-12 GBq/μmol (n = 5) and 6-8 GBq/μmol (n = 4), respectively. In biodistribution studies, radioligands [18F]4 and [18F]5 showed moderate brain uptake in male ICR mice with 1.52 ± 0.15 and 0.91 ± 0.07% ID/g, respectively, at 15 min. Metabolic stability studies in mouse brain revealed that [18F]4 exhibited high stability while [18F]5 suffered from low stability. Higher accumulation of [18F]4 in the brain of lipopolysaccharide (LPS)-treated mice was observed, and further pretreatment of BLZ945 or CPPC led to remarkable reduction, indicating specific binding of [18F]4 to CSF-1R.
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Affiliation(s)
- Xiaodan An
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jingqi Wang
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Linjiang Tong
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Xiaojun Zhang
- Nuclear Medicine Department, the First Medical Center of Chinese PLA General Hospital, Beijing 100853, China
| | - Hualong Fu
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Jinming Zhang
- Nuclear Medicine Department, the First Medical Center of Chinese PLA General Hospital, Beijing 100853, China.
| | - Hua Xie
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Yiyun Huang
- Yale PET Center, Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT 06520-8048, USA.
| | - Hongmei Jia
- Key Laboratory of Radiopharmaceuticals (Beijing Normal University), Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
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14
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Pees A, Chassé M, Lindberg A, Vasdev N. Recent Developments in Carbon-11 Chemistry and Applications for First-In-Human PET Studies. Molecules 2023; 28:molecules28030931. [PMID: 36770596 PMCID: PMC9920299 DOI: 10.3390/molecules28030931] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 01/09/2023] [Accepted: 01/10/2023] [Indexed: 01/19/2023] Open
Abstract
Positron emission tomography (PET) is a molecular imaging technique that makes use of radiolabelled molecules for in vivo evaluation. Carbon-11 is a frequently used radionuclide for the labelling of small molecule PET tracers and can be incorporated into organic molecules without changing their physicochemical properties. While the short half-life of carbon-11 (11C; t½ = 20.4 min) offers other advantages for imaging including multiple PET scans in the same subject on the same day, its use is limited to facilities that have an on-site cyclotron, and the radiochemical transformations are consequently more restrictive. Many researchers have embraced this challenge by discovering novel carbon-11 radiolabelling methodologies to broaden the synthetic versatility of this radionuclide. This review presents new carbon-11 building blocks and radiochemical transformations as well as PET tracers that have advanced to first-in-human studies over the past five years.
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Affiliation(s)
- Anna Pees
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, ON M5T 1R8, Canada
| | - Melissa Chassé
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, ON M5T 1R8, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Anton Lindberg
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, ON M5T 1R8, Canada
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health (CAMH), Toronto, ON M5T 1R8, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A8, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada
- Correspondence:
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15
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Boyle AJ, Murrell E, Tong J, Schifani C, Narvaez A, Wuest M, West F, Wuest F, Vasdev N. PET Imaging of Fructose Metabolism in a Rodent Model of Neuroinflammation with 6-[ 18F]fluoro-6-deoxy-D-fructose. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238529. [PMID: 36500626 PMCID: PMC9736258 DOI: 10.3390/molecules27238529] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022]
Abstract
Fluorine-18 labeled 6-fluoro-6-deoxy-D-fructose (6-[18F]FDF) targets the fructose-preferred facilitative hexose transporter GLUT5, which is expressed predominantly in brain microglia and activated in response to inflammatory stimuli. We hypothesize that 6-[18F]FDF will specifically image microglia following neuroinflammatory insult. 6-[18F]FDF and, for comparison, [18F]FDG were evaluated in unilateral intra-striatal lipopolysaccharide (LPS)-injected male and female rats (50 µg/animal) by longitudinal dynamic PET imaging in vivo. In LPS-injected rats, increased accumulation of 6-[18F]FDF was observed at 48 h post-LPS injection, with plateaued uptake (60-120 min) that was significantly higher in the ipsilateral vs. contralateral striatum (0.985 ± 0.047 and 0.819 ± 0.033 SUV, respectively; p = 0.002, n = 4M/3F). The ipsilateral-contralateral difference in striatal 6-[18F]FDF uptake expressed as binding potential (BPSRTM) peaked at 48 h (0.19 ± 0.11) and was significantly decreased at one and two weeks. In contrast, increased [18F]FDG uptake in the ipsilateral striatum was highest at one week post-LPS injection (BPSRTM = 0.25 ± 0.06, n = 4M). Iba-1 and GFAP immunohistochemistry confirmed LPS-induced activation of microglia and astrocytes, respectively, in ipsilateral striatum. This proof-of-concept study revealed an early response of 6-[18F]FDF to neuroinflammatory stimuli in rat brain. 6-[18F]FDF represents a potential PET radiotracer for imaging microglial GLUT5 density in brain with applications in neuroinflammatory and neurodegenerative diseases.
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Affiliation(s)
- Amanda J. Boyle
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON M5T 1R8, Canada
- Correspondence: (A.J.B.); (N.V.); Tel.: +1-416-535-8501 (ext. 30884) (A.J.B.); +1-416-535-8501 (ext. 30988) (N.V.)
| | - Emily Murrell
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Junchao Tong
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Christin Schifani
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Andrea Narvaez
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
| | - Melinda Wuest
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2N4, Canada
| | - Frederick West
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2N4, Canada
- Department of Oncology, University of Alberta, Edmonton, AB T6G 1Z2, Canada
| | - Frank Wuest
- Department of Chemistry, University of Alberta, Edmonton, AB T6G 2N4, Canada
- Department of Oncology, University of Alberta, Edmonton, AB T6G 1Z2, Canada
| | - Neil Vasdev
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, 250 College St., Toronto, ON M5T 1R8, Canada
- Department of Psychiatry, University of Toronto, 250 College St., Toronto, ON M5T 1R8, Canada
- Correspondence: (A.J.B.); (N.V.); Tel.: +1-416-535-8501 (ext. 30884) (A.J.B.); +1-416-535-8501 (ext. 30988) (N.V.)
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